(600c) Low-Cost Oxygen Carrier Materials for Chemical-Looping Combustion of Biomass

Chemical-looping combustion (CLC) is one of the most promising methods to implement carbon capture technologies to mitigate CO₂emissions from thermochemical fuel conversion.

The solid oxygen carrier is a core component of every CLC system and the choice of the oxygen carrier depends on the fuel and operation conditions. When it comes to conversion of solid fuels, low-cost oxygen carriers seem to be more suitable. This is because the lifetime of an oxygen carrier in a CLC system may be limited by side reactions with fuel ash, or by carryover losses in the ash separation.

Hence the use of low cost oxygen carrier materials is preferred, lowering the economic and technologic effort connected to higher demands of make up.

Due to its carbon neutrality, the use of biomass in carbon capture strategies leads to net negative emissions. However, the ash of biomass is known to be more reactive and has generally lower softening and melting temperatures than most coals. This makes biomass combustion units more prone to defluidization, slagging and fouling and corrosion. If biomass should be used as fuel the temperature is usually kept at lower levels to overcome these problems.

In the present contribution different low cost oxygen carrier materials are investigated with respect to their reactivity at different temperatures. The data is obtained from experiments carried out in a quartz glas reactor under fluidized bed conditions. The bed temperature was set to 700, 800, 850 and 950°C, respectively. The perforance was tested with volatile components and in selected cases the influence of the char gasification has been investigated separately. Before the actual experiments, the oxygen carrier materials were activated at 850 and 950°C using a mixture of H₂ and CO as fuel.